surface frictional coefficients. However, aside from planets with largely uniform oceans, these models are not obviously useful when it comes to understanding the impact of climate on biodiversity. Here, we show that contrary to expectation, the aquaplanet models can be directly applied to planets with a variety of land areas, with little need for modification. Using this premise, this paper provides a simple mathematical framework that may be applied to more complex planetary surfaces and identifies the majority of the climate-model components that are needed to accurately determine the biological potential of habitable exoplanets. As a proof- of-concept, an available climate model for Proxima b is used to determine its biological potential, given a suitable atmosphere.

Stewart, T.A., Lemberg, J.B., Taft, N.K., Yoo, I., Daeschler, E.B., Shubin, N.H., 2020. Fin ray patterns at the fin-to- limb transition. Proceedings of the National Academy of Sciences 117, 1612-1620.

https://doi.org/10.1073/pnas.1915983117 Significance: To explain how limbs evolved from fins, paleontologists have traditionally studied the endoskeleton. Here, we provide a comparative analysis of the other skeletal system of fins, the dermal skeleton. We describe dermal ray anatomy for 3 species of tetrapodomorph fishes. These data show that, prior to the origin of digits, dermal rays were simplified, the fin web became reduced in size, and the top and bottom of the fin became more asymmetric. These changes reveal how fins became adapted for interacting with the substrate prior to the fin-to-limb transition and that dorsoventral asymmetry is an important, understudied axis of diversification in paired fins. Abstract: The fin-to-limb transition was marked by the origin of digits and the loss of dermal fin rays. Paleontological research into this transformation has focused on the evolution of the endoskeleton, with little attention paid to fin ray structure and function. To address this knowledge gap, we study the dermal rays of the Sauripterus taylori Eusthenopteron foordi pectoral fins of 3 key tetrapodomorph taxa - (Rhizodontida), Tiktaalik roseae (Tristichopteridae), and (Elpistostegalia) - using computed tomography. These data show several trends in the lineage leading to digited forms, including the consolidation of fin rays (e.g., reduced segmentation and branching), reduction of the fin web, and unexpectedly, the evolution of asymmetry between Eusthenopteron dorsal and ventral hemitrichia. In , dorsal rays cover the preaxial endoskeleton slightly more Tiktaalik than ventral rays. In , dorsal rays fully cover the third and fourth mesomeres, while ventral rays are restricted distal to these elements, suggesting the presence of ventralized musculature at the fin tip analogous to Eusthenopteron a fleshy 'palm.' Asymmetry is also observed in cross -sectional areas of dorsal and ventral rays. Tiktaalik dorsal rays are slightly larger than ventral rays; by contrast, dorsal rays can be several times larger than ventral rays, and degree of asymmetry appears to be greater at larger sizes. Analysis of extant osteichthyans suggests that cross-sectional asymmetry in the dermal rays of paired fins is plesiomorphic to crown group osteichthyans. The evolution of dermal rays in crownward stem tetrapods reflects adaptation for a fin-supported elevated posture and resistance to substrate-based loading prior to the origin of digits.

Striolo, A., 2019. Clathrate hydrates: recent advances on CH and CO hydrates, and possible new frontiers. 4 2 Molecular Physics 117, 3556-3568. https://doi.org/10.1080/00268976.2019. 1646436

Gas hydrates continue to attract enormous attention throughout the energy industry, as both a hindrance in conventional production and a substantial unconventional resource. Scientists continue to be fascinated by the hydrates' ability of sequestering larg e amounts of hydrophobic gases, unusual thermal transport properties and unique molecular structures. Technologically, clathrate hydrates promise advantages in applications as diverse as carbon sequestration and water desalination. The communities interested in hydrates span traditional academic disciplines, including earth science, physical chemistry and petroleum engineering. The studies on this field are equally diverse, including field expeditions to attempt the production of natural gas from hydrate deposits accumulated naturally on the seafloor, to lab-scale studies to exchange CO for CH in hydrates; from 2 4 theoretical studies to understand the stability of hydrates depending on the guest molecules, to molecular simulations probing nucleation mechanisms. This review highlights a few fundamental questions, with focus on knowledge gaps representing some of the barriers that must be addressed to enable growth in the practical